title: Isolation and characterization of the carbon-phosphorus bond-forming enzyme phosphoenolpyruvate mutase from the mollusk Mytilus edulis.
abstract: The enzyme phosphoenolpyruvate mutase was purified to homogeneity from the mollusk Mytilus edulis. The subunit size of the native homotetramer was determined to be 34,000 Da. The steady-state kinetic constants for catalysis of the conversion of phosphonopyruvate to phosphoenolpyruvate at pH 7.5 and 25 degrees C were measured at kcat = 34 s-1, phosphonopyruvate Km = 3 microM, and Mg2+ Km = 4 microM. The enzyme displayed a broad specificity for divalent metal ion activation; Co2+, Mn2+, Zn2+, and Ni2+ are activators, whereas Ca2+ is not. Analysis of the pH dependence of the Mg2+-activated mutase-catalyzed reaction of phosphonopyruvate revealed one residue that must be protonated (apparent pKa = 8.3) and a second residue that must be unprotonated (apparent pKa = 7.7) for maximal catalytic activity.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: A
authors.initials: A
authors.lastname: Kim
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: B M
authors.initials: BM
authors.lastname: Martin
authors.forename: D
authors.initials: D
authors.lastname: Dunaway-Mariano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D002244:Carbon / Q000378:metabolism*; D002384:Catalysis; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D010758:Phosphorus / Q000378:metabolism*; D017875:Phosphotransferases (Phosphomutases) / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D010758:Phosphorus; D002244:Carbon; D017875:Phosphotransferases (Phosphomutases); C057167:phosphoenolpyruvate mutase